The present invention relates generally to surface maintenance or conditioning machines, and particularly those machines employing one or more surface maintenance or conditioning appliances or tools that perform one or more tasks including, among others, scrubbing, sweeping, and polishing or burnishing. More specifically, the present invention is particularly directed to a variable down-force coupling system for such surface conditioning machines.
Surface maintenance vehicles that perform a single surface maintenance or surface conditioning task are, of course, well known. Surface maintenance vehicles are generally directed to perform work in diverse maintenance, conditioning and cleaning applications such as for flooring surfaces. In this disclosure, the term floor refers to any support surface, such as, among others, floors, pavements, road surfaces, ship decks, and other surfaces to be cleaned and the like.
Commonly floor or surface maintenance machines are constructed having a single surface conditioning appliance or system so as to only sweep, others to scrub, while still others only to polish or burnish. It is of course possible to construct a single surface maintenance machine to perform one or more of the aforementioned surface maintenance tasks. One example of a multi-task floor conditioning machine is disclosed in U.S. Pat. No. 3,204,280, entitled xe2x80x9cFloor Cleaning and Waxing Machine,xe2x80x9d the entire disclosure of which is incorporated by reference herein in its entirety for any and all purposes. Another is disclosed in U.S. Pat. No. 5,483,718, entitled, xe2x80x9cFloor Scrubbing Machine Having Impact Energy Absorbtion,xe2x80x9d the entire disclosure of which is incorporated be reference herein in its entirety for any and all purposes. Disclosed therein is a forward mounted scrubber assembly that is followed by a squeegee assembly.
Scrubbing systems are well known in the art. Scrubbing systems commonly include a driver assembly and a rotatable scrubber in the form of a brush, pad, or the like. A control device may be utilized for controlling the degree of scrubbing (typically a function of down-force applied through the scrubber) applied to a floor surface depending upon the type and/or condition of floor surface intended to be scrubbed. The scrubber driver assemblies for scrubbing systems are well known in the art and commonly include one or more rotatable brushes driven by a driver motor affixed to a scrubber head. Scrubber heads of the prior art have been selectively raised and lowered by an actuator coupled to the driver so as to achieve an intended down force or scrubbing pressure of the srub pad against a floor surface. Examples of the latter are taught in U.S. Pat. Nos. 4,757,566, 4,769,271, 5,481,776, 5,615,437, 5,943,724, and 6,163,915, the entire disclosures of which are incorporated by reference herein in its entirety for any and all purposes. Common to some of the control systems of the aforementioned prior art is the employment of a current sensor that monitors the current drawn by the driver motor. In some of the aforementioned systems of the prior art a xe2x80x9cpressure sensorxe2x80x9d is employed that is representative of the pressure of the scrubber head against the floor. Still others attempt to control torque load on the motor indicated by the sensed motor current.
The present invention relates to an efficient structure for controlling the down force of a working head in engagement with a surface to be cleaned, maintained, or otherwise conditioned. The invention further relates to a method of engaging and using such a control structure to perform surface cleaning, surface maintenance, surface conditioning and the like. While the present invention is described and depicted primarily with reference to a cleaning head having dual rotary scrubbing brushes, the present invention finds diverse application in the art of surface cleaning, maintenance, conditioning and the like. Accordingly, the present invention is readily adaptable to cleaning heads having one or more of the following applications, including without limitation, such cleaning heads designated and adapted to: burnish, polish, scrub, sweep, brush, treat and wipe a surface to be cleaned wherein an ability to control the downforce of the head is beneficial. Of course, such cleaning head implements or cleaning head appliances may each be provided with an embodiment of the present invention and coupled to a single dedicated surface maintenance vehicle or to more than one such cleaning head coupled to a single vehicle.
In one embodiment, the invention is particularly applicable to a floor scrubbing machine having a scrub head mounted in front of the machine chassis. The scrub head includes a scrub brush or pad and a scrub driver. A linear actuator is utilized to raise and lower the scrub head relative to the floor surface. The scrub head has a predetermined weight which may be supported by the scrub brush in a first operational mode of use. In the first operational mode of use, the scrub head is floatingly supported by the machine so that the scrub head can follow the contours or undulations of the floor surface. In this mode of operation vertical movement of the scrub head relative to the machine is relatively unconstrained. In a second operational mode of use the floor scrubbing machine additionally engages the linear actuator for use in a second operational mode of use. In the second mode of use, the linear actuator may be engaged to transfer additional force to the scrub head, increasing the down force supported by the scrub pad, and increasing the relative scrubbing work performed by the machine. In the second mode of operation, movement of the scrub head relative to the machine is relatively constrained by the linear actuator
One aspect of the present invention is the provision of a mechanical system for transferring between the first and second operational modes of use. An operator manipulable element may be utilized to change from the first operational mode of use to the second operational mode of use. An automatic disengagement for returning the machine to the first operational mode of use is also provided by one aspect of the present invention. In one embodiment, the automatic disengagement is in response to the scrub head being raised away from the floor surface toward its transport position.
The present invention provides several advantages over both prior art and contemporary apparatus for controlling the down force, and hence scrub pressure of a cleaning head coupled to a cleaning machine. The present invention may be implemented without a sophisticated electronic control. As a result the present invention is generally lower cost, easier to maintain and less prone to breakage than prior art (and complex contemporary) cleaning head control mechanisms and algorithms.